1. Field of the Invention
This invention generally relates to wind turbines and more particularly to a wind turbine having a control vane for moving the turbine away from a reversal wind vector.
2. Description of Related Art
The following art defines the present state of this field:
Sherwood, U.S. Pat. No. 244,677 describes a horizontal windmill, the combination, with a staudard and a vertical shaft, of one or more sets of fixed radial arms secured on squared portions of said vertical shaft, each fixed arm having a hinged arm provided with wings adapted to automatically open and close, substantially as set forth.
Rue, U.S. Pat. No. 749,806 describes a device the combination of a rotary frame, shafts journaled op the frame and provided with means for engaging the same for limiting their rotation, blades mounted on the shafts and capable of rotating independently of the same, and springs housed within the blades with and connected to the shafts and maintaining the same normally in operative position, substantially as described.
Gemeny, U.S. Pat. No. 2,030,953 describes an automatic self-adjusting variable pitch propeller having a hub portion, and a plurality of blades having shanks mounted for turning movement in the hub for variation of the pitch of the propeller, weight lever means connecting relatively opposite sides of different blades for balancing out centrifugal forces tending to turn the blades in the hub when the propeller is operated, and means cooperating with the blades controlling the pitch of the propeller in relation to the air forces acting thereon when the propeller is operated.
Ellwood, U.S. Pat. No. 2,052,454 describes a propeller, a rotary shaft, a blade carrying ring carried by said shaft; a synchronizing disk rotatable with respect to said ring and having tangentially disposed slots, coupling yokes swiveled in said slots, pitch changing shafts radially supported with relation to said ring, tubular stems about said pitch changing shafts, propeller blades rotatable about and shiftable on said stems and having the pitch changing shafts fixed thereto, hubs fixed to said pitch changing shafts and having spiral connections with the stems, spring tensioned means connected with the ring; and disk for normally holding the coupling yokes at the inner ends of the tangential slots in said disk, the blades having wider portions at their outer ends and provided with longitudinal slots accommodating said stems, and weights on the wider ends of said blades.
Watkins, U.S. Pat. No. 2,080,955 describes a device including: a generator; an armature shaft for the generator; a wind driven propeller mounted on the armature shaft; pivoted blades on the propeller; a yielding connection between the propeller and shaft; and means of such a character that increased load in the generator will operate through said yielding connection to pivot the blades of the propeller to retard the speed thereof.
Andersen, et al., U.S. Pat. No. 3,580,694 describes a combined fluid impeller and self-sealing closure having a plurality of blades mounted on the periphery of a rotor ring for pivotal movement about a radial axis. The blades are arranged so that they are in overlapping, sealing relationship with respect to one another when the impeller is at rest, and are in an open, impelling position when the impeller is rotating. The blades are opened by means of weights arranged in the rotor ring which are moved by centrifugal force when the impeller is rotating and rotates a control member arranged inside the rotor ring which in turn rotates the blades to their open position.
Norz, U.S. Pat. No. 4,084,921 describes a mechanism for turning a horizontal axis rotor windmill into the direction of the wind, either under the instruction of a small pilot vane, or automatically without the use of such vane. This is accomplished by cyclically controlling the pitch of the rotor blades during revolution whereby to decrease the gyro forces on the rotor when yawing, as well as to take advantage of the force of the wind on the blade to assist turning the axis into the wind. The mechanism of the present invention automatically and cyclically alters the pitch of the blades as the yaw angle of the wind changes so as to present a cyclically different angle of attack between the blades and the wind, thus utilizing the force of the wind to cause the turning of the axis of the rotor into the wind.
Trainer, U.S. Pat. No. 4,306,838 describes force transferring elements which include a metal or plastic hub deep drawn or elongated with a flange extending therefrom and functioning as a force transferring element. The hub and flange may be of one piece with the flange having blades extending outwardly from the hub, the hub around its circumference being provided with a plurality of indented portions or corrugations to provide a spring action for engagement with a shaft. In another form of the invention two similar pieces are utilized each with a deep drawn or elongated hub and having outer rims which together receive a V-belt or the like. The elements may be connected to a shaft for input to the shaft, or may be carried on the shaft as energy converting or driving members.
Burkett, U.S. Pat. No. 4,877,374 describes a windmill which automatically compensates for increased wind velocity, causing the blades to feather and rotate at a substantially constant velocity rather than overspeeding. This is accomplished by pivotally mounting the blades so that they are rotatable between positions of relatively high angle with respect to the direction of the wind and positions of relatively shallow angle, with a resilient means biasing them to the former position. Tabs projecting forwardly at obtuse angles from the outer ends of the leading edges of the blades cause the blades to be pivoted to the feathered position when wind velocity increases.
Lund, U.S. Pat. No. 5,137,417 describes a wind energy conversion system including specially shaped blades mounted in a specific location on a specially shaped blade-supporting body to maximize energy conversion from wind energy to electrical energy. The blade-supporting body includes a concave section located upstream of a convex section, with the two sections being joined together at a location of maximum diameter. The blades are mounted on the body at the location of maximum diameter. Each blade includes two surfaces each of which includes a concave section and a convex section. The blade surfaces are spaced apart from each other by a blade thickness dimension that increases from essentially zero at blade tips to a maximum adjacent to a blade longitudinal axis that extends from a blade proximal end mounted on the blade-supporting body to a distal end spaced from said blade-supporting body.
Steward, U.S. Pat. No. 5,286,166 describes an automatic centrifugal force variable pitch propeller assembly including a plurality of propeller blades mounted within a housing, each of the propeller blades being mounted to permit limited radial travel in its entirety and simultaneous incremental rotation about its longitudinal axis, the limited radial travel of each of the propeller blades in its entirety being caused by a centrifugal force developed by rotation of the propeller assembly and extending between an inward position corresponding to rotation of the propeller assembly at an idle speed and outward position corresponding to rotation at a maximum speed. The propeller assembly includes a pitch change mechanism that is coupled to the shaft end of each of the propeller blades and is solely responsive to radial travel of each of the propeller blades, caused by the centrifugal forces developed by rotation of the propeller assembly, for causing an identical predetermined incremental rotation of each of the propeller blades about its longitudinal axis that is a nonlinear function of the radial travel of each of the propeller blades. The propeller assembly also includes a rigid mechanical interconnection between the shaft ends of each of the propeller blades to insure that the propeller blades travel radially in their entirety in concert with each other to provide fail safe operation of the propeller assembly.
Lund, U.S. Pat. No. 5,599,168 describes a wind turbine apparatus having a frame assembly consisting of a hub and an outer rim interconnected by a series of spokes. Several wind vanes are rotatably secured within the frame assembly so as to extend from the hub radially outwardly around the frame assembly. Each wind vane consists of an impeller and an impeller shaft, the impeller shaft being positioned so that it does not pass through the center of wind moment of the impeller. Thus, when a wind vector reaches the impeller, the impeller and shaft rotate in direct accordance with the wind's velocity, thus ensuring that the impeller faces optimally into the wind. A biasing device is attached to each impeller shaft, the biasing device serving to retard the rotation of the wind vanes when the wind vector exceeds a given velocity, thus ensuring that the impellers maintain a constant rotational speed. A link means interconnects the adjacent impeller shafts so as to ensure that the wind vanes rotate simultaneously.
The prior art teaches wind wheels, windmills, automatic variable pitch propellers, propeller governors, fluid impellers having self-sealing closures, feathering blades, self directing windmills, wind energy converters, and wind turbine adaptable to wind direction, but does not teach the present invention with capacity for detecting a wind reversal and for thereafter moving under wind force to a normal wind flow position. The present invention fulfills these needs and provides further related advantages as described in the following summary.